Recent evidence in vivo and in vitro suggests that one or more metabolites of arachidonic acid may act as local inhibitors of glucose-stimulated insulin secretion and may contribute to the defective insulin secretion characteristic of type II (non-insulin-requiring) diabetics. Furthermore, glucose itself may alter arachidonic acid release and/or metabolism within the pancreatic islet in such a way as to complete a negative feedback loop. Testing this hypothesis demands a thorough understanding of arachidonic acid metabolism in the islet. Thus, this proposal is focussed on an examination of the metabolism of tritiated arachidonic acid by islet cells both basally and in response to stimuli known to alter beta cell responses, especially glucose. Identification of arachidonic acid metabolites will be achieved using high performance bound chromatography which employs a reversephase mode. These results will be confirmed by radioimmunoassay and mass spectrometry. The cells studied will be (a) monolayer cultures of neonatal rat pancreatic cells (a system which we have extensively characterized and in which a modulatory role of prostaglandin E on insulin release has been demonstrated), (b) intact rat islets (to obviate the problem of contamination of the first cell preparation by non-endocrine cells). When the synthetic capability of islet cells has been identified, the cells will be treated with each of several pharmacologic agents to selectively perturb the sytem. The effect on insulin secretion of alterations in the absolute or relative amounts of cyclo-oxygenase or lipoxygenase products will be studied. These studies (in conjunction with selective exogenous repletion of various arachidonic acid metabolites) will be used to identify the product(s) responsible for the observed alterations in insulin relase.